Harry Potter and the Irrational Odyssey
by ElizabethRobinThales
Summary: A sequel to Harry Potter and the Methods of Rationality. Harry has emerged victorious and is now on course to bring about a global-scale paradigm shift. Or is he? What if things aren't as they appear? What if Harry misinterpreted the riddle?


Disclaimer: J.K. Rowling owns Harry Potter. Eliezer Yudkowsky created the timeline we're branching off from. Simon Renard de St. André painted the vanitas I'm using for the cover image.

You should seriously consider reading _Harry Potter and the Methods of Rationality_ before reading this story. It isn't entirely necessary to have done so in order to follow the plot, but you're gonna have _massive_ plot points in HPMOR spoiled if you try to read HPIO first.

The Last Enemy is still loose in the world. Mors fontis Omnia.

* * *

 _The sound of gunfire rang in her ears as she took cover behind a desk in the corner of the room. She reached into her pouch and drew forth the wax-sealed paper, on the surface of which was inscribed simply the number 42. She broke the seal and began to read..._

 _... Wait, what? He couldn't have possibly known..._

 _When could he have..._

* * *

 **HARRY POTTER**

 **AND**

 **THE IRRATIONAL ODYSSEY**

Book One: Everything Not Forbidden is Compulsory

* * *

Upon a roof floored in square stone tiles, under the bright morning sun, Harry stood facing Hermione across crossed wands.

"Can you at least not say anything about 'until death takes me', because did I mention I have the Philosopher's Stone now? Or anything about 'the end of the world and its magic'?" He raked his free hand through his hair and gave a sheepish grin. "I'm a lot more nervous around phrases like that than I used to be."

"Well, maybe after this you'll be less nervous," said Hermione. "I _do_ choose this, now." A strong breeze caught her hair, and her chestnut curls billowed around her shoulders like reeds in a summer storm. When she spoke again, her voice was level and precise. "Upon my life and magic I swear friendship to Harry Potter, to help him and trust in him, to stand with him and stand by him, and sometimes go where he can't go, till the day that death takes me for real - if it ever really does, I mean." She was silent for a moment, then smiled. "And if the world or its magic ends, we'll deal with that together."

A huge smile lit Harry's face, the widest he had ever smiled in his life. Whatever problems might lie ahead, he no longer doubted that he'd be able to maintain what Dumbledore had set in motion. Hermione had been right, he felt much less nervous now about the prophesied destruction of the -

 _If this were a story, that oath would have been The End._

Harry blinked.

 _What? Why did I just think that?_ He frowned at the strange little thought, annoyed that his brain had interrupted itself with such an irrational non sequitur. _I suppose it_ does _fit the pattern..._

The trees far below rustled gently in the crisp morning air, drawing Harry's mind back to the here and now. Spring was rolling into summer in the Scottish Highlands; the wind was light and cool, the sun mild and warm, and Hermione's Magical Aura of Innocence and Purity™ was filling him with a sense of calm peace. It was all too easy to disregard a vague apprehension - especially one so odd - and shove it into the back of his mind.

Harry turned his head to gaze out towards the horizon. Thoughts of the future pervaded his mind - Hermione, the Philosopher's Stone, all of the revolutionary things the three of them were going to accomplish together - and he couldn't help but smile again. He thought of the stars, and he thought of the prophecy.

 _HE IS HERE. THE ONE WHO WILL TEAR APART THE VERY STARS IN HEAVEN. HE IS HERE. HE IS THE END OF THE WORLD._

He felt much less nervous now about the prophesied destruction of the world at his own hands. Hermione having her own horcrux (and having been imbued during the resurrection ritual with the attributes of both a unicorn and a troll) made it _exceedingly_ unlikely that she'd be dying again any time soon - she would always be there to help him steer the narrow line of Time through fate's narrow keyhole. The old world would end via a paradigm shift, a complete overhaul of the fundamental infrastructure of civilization, fulfilling the prophecy in the only way that ensured humanity's continued existence. However long it took, they would find a way to merge the magical and muggle worlds and make the Stone's healing available to _everyone_ , not just the wizards, and then - Well, it was obvious enough if you'd grown up with the right sort of upbringing. Humanity was destined to colonize the cosmos sooner or later, and they'd be starting as soon as possible if Harry had any say in the matter.

 _A global society of immortal wizards, spreading throughout the galaxy... I can't believe this is real_ , Harry thought. _The Stone isn't quite exactly an Instant Global Victory Condition, but - eventually - we're going to optimize literally everything._

He turned back again to face Hermione.

The young witch didn't turn her head from where she had been gazing at the horizon, her face impassive. "Have you quite finished your internal monologue, Mr. Potter?"

Harry froze where he stood.

A roguish grin crossed Hermione's face, and she giggled.

After a moment, Harry chuckled.

Then both were laughing, and all was right with the world.

The boy and the girl gazed into each other's eyes, grinning.

" _Thank you_ , Hermione," Harry said. "For _everything_. And you really _did_ say just exactly what I needed to hear. You were right, I feel a lot less nervous now."

The smile left the girl's face. "I should hope so." Her voice grew a bit cold, took on a sardonic tinge, and her aura drew back and diminished. "I specifically wrote that oath in order to elicit happiness and hope within your mind, to bring you to an emotional apogée. There's nowhere left to go from here but _down_."

A chill went down Harry's spine then.

An intimation of something dreadful approaching.

A creeping terror.

Harry's eyes widened in sudden horror; it was impossible not to notice that familiar crawling sensation on his skin, not to recognize the familiar cadence that crept into Hermione's voice. " _Voldemort._ " He spat the word as though it were profane.

Hermione's lips twisted into a discordantly mirthless grin. "Indeed."

A snarl contorted Harry's face. "How _dare_ you use her body for -"

"Not an unreasonable assumption," Hermione's voice interrupted. "But no, I didn't resurrect her to use as a host. In point of fact, she was never resurrected in the first place."

 _What?_

"Your subjective experience of the past 36 hours has, in reality, taken place over the course of approximately 15 minutes. This -" Hermione's hand raised in a broad sweeping gesture over the horizon, out towards the trees and lakes and hills far below - "is naught but an exceptionally intricate False Memory Charm."

The sun began to rise noticeably faster.

Clouds formed and dissipated at an alarming rate.

Harry opened his mouth to speak - or rather, _he felt the intention to open his mouth,_ but it seemed to be taking quite a bit longer than usual for his lips to part. _If the world seems to be speeding up around me, I must be slowing down..._

"Tell me, Mr. Potter - did you feel _happy?_ " The Dark Lord laughed, a hollow noise that didn't quite fit Hermione's vocal cords, and the world was plunged into darkness.

o - o - o - o - o

Harry's eyes flew open, revealing cold stone walls tinted blood-red by the light of a Fiendfyre phoenix. A sharp sense of catastrophe broke over him like thunder, triggering a flash of pain in the scar on his forehead. He staggered, his mind disoriented by the instantaneous shift from calm to calamity, made all the more acute by the void left in the absence of Hermione's aura.

 _It was never_ her _aura_ , Harry thought bitterly. _It was a lie. It was all a lie._

Anger mingled with the adrenaline in his veins. His hands clenched into fists at his sides, the nails digging deep into his palms, and he became aware of the steel ring on his left pinky finger. He glanced down at the gem - no longer emerald green, but chestnut brown - and a hard expression crossed his face.

 _She's still dead... And the Stone, and Dumbledore's letters, and the Line of Merlin, and Azkaban - None of it was real._

More or less on autopilot, Harry cast his gaze around the room, his eyes absently searching for the source of the familiar tension in the air. His thoughts still came slowly, as though his brain had been dipped in molasses; but the sense of doom was tangible, pressing down on him like a cast-iron bacon press, and he knew that any moment now -

"Mr. Potter," said a high, cold voice close behind him. "Turn around."

Coldness began to settle into Harry's blood, the dark crystalline clarity already organizing his thoughts and attempting to map out a solution that involved incapacitating Voldemort without preventing him from resurrecting Hermione. A wave of black rage washed through him, a rising fury, and he stopped himself. _I can't do_ _this_. He tried to let go, to let some of the coldness drain away, and regained himself. He had already determined that his 'mysterious dark side' was nothing more than an inherited pattern of cognition, a side effect of Tom Riddle's attempt to copy himself onto the infant Harry Potter's brain. Calling upon that aspect of his personality seemed... wrong. And if Voldemort had this level of control over his mind, immersing himself in the coldness wasn't going to help either way.

Harry took a breath and steeled his will, and prepared to turn around to face the inevitable. _Alright... Apparently there's nothing I can do to extricate myself from this situation, no action I can take that won't be anticipated or countered -_

"That is, to be concise, an accurate evaluation of the current state of the gameboard."

" _What?_ " Harry swung around in shock. Leaning against the stone wall, the Dark Lord gazed at Harry from behind the mask of Quirinus Quirrell, his expression indecipherable in the crimson light. Harry gaped at him, his mind wobbling in confusion. "That's impossible."

The Dark Lord's lips twitched. "Child, you have _no idea_ what's possible."


End file.
